Complex regional pain syndrome (CRPS) is a chronic (long-term) disorder of the nervous system. It is a collection of signs and symptoms typically at the site of an injury to an arm or leg. Those symptoms may include burning-type pain, changes in skin and bone tissue, excessive sweating, swelling of an extremity, and extreme sensitivity to touch.
CRPS is poorly understood and difficult to diagnose. Better treatment outcomes are more likely if treatment is started during the first three months of the condition.
Although it can start at any age CRPS is most common between the ages of about 40 and 50 years. It is rare in the elderly and very few children are affected. CRPS occurs more frequently with women than men.
CRPS was first recorded in the 19th century during the American Civil War. Doctors noted veterans were experiencing pain after their wounds had healed. CRPS shares many features with fibromyalgia, which is another type of pain syndrome.
The exact cause of CRPS is unknown but in most cases the condition is triggered by trauma or injury causing damage to, or malfunction of, the nervous system.
CRPS has traditionally been divided into two types, which have similar signs and symptoms but different causes: CRPS I occurs after an illness or injury that doesn’t directly damage nerves; CRPS II occurs after direct nerve damage.
In more than 90% of cases, CRPS is triggered by a clear history of trauma to an extremity (ie: CRPS I). These include:
- Bruise or crush injury
- Sprains or strains
CRPS also affects the immune system. High levels of inflammatory chemicals contribute to the redness, swelling, and warmth reported by many patients. Also, CRPS appears to be more common in individuals with other inflammatory and autoimmune conditions.
Emotional stress or trauma can be a trigger for CRPS.
Signs and symptoms
CRPS can affect the nerves, skin, muscles, blood vessels, and bones simultaneously. Symptoms can be gradual or rapid in onset and can vary in severity.
The primary symptom of CRPS is prolonged severe pain, which is often described as a burning, throbbing, or tingling sensation, usually in an arm, leg, hand or foot. In some people the affected area becomes hypersensitive with normal contact with the skin being experienced as intense pain (allodynia).
Other signs and symptoms of CRPS include:
- Sensitivity to touch or cold
- Swelling of the painful area
- Changes in skin temperature
- Abnormal sweating (hyperhidrosis) in the affected or surrounding areas
- Changes in skin colour, ranging from white and blotchy to blue, purple, or red
- Changes in skin texture in the affected area, which may appear thin or shiny
- Changes in hair and nail growth patterns
- Joint stiffness and swelling
- Tremors or jerking (spasm) of the affected limb
- Reduced ability to move the affected body part.
Variations in skin temperature, skin colour, or swelling of the affected limb are due to abnormal circulation caused by damage to the nerves that control blood flow and temperature.
CRPS is poorly understood and often misdiagnosed. As there is no definitive test for CRPS, diagnosis is usually made based on pain symptoms and clinical signs. A doctor will usually make a diagnosis of CRPS based on the following:
- A full medical history and physical examination
- Discussion of current pain symptoms
- X-rays and magnetic resonance imaging (MRI) scans to assess bone changes
- Sympathetic nervous system tests to detect impaired function of the sympathetic nervous system, which regulates the body's unconscious functions like heart rate and blood flow.
- Blood tests to rule out other causes.
Treatment is generally most effective in the first three months of the condition. Without prompt treatment, CRPS can lead to tissue wasting (atrophy), including the skin, muscle, and bones; and muscle tightening (contracture). If left untreated the disorder can spread to other areas of the body. The usual pattern of spread is up the affected extremity and on to the same side of the body. It may also spread to the opposite side of the body. Specialist intervention early on is the key to a successful outcome.
A doctor may need to try a variety of treatments. Least invasive is the application of cold or heat. Other treatments include:
- Sympathetic block (injection of a local anaesthetic into affected sympathetic nerves to block pain)
- The use of low doses of tricyclic antidepressants and anticonvulsants to relieve pain sensitivity
- Pain medications including topical anaesthetic creams (eg: lidocaine) and non-steroidal anti-inflammatory drugs (NSAIDs, eg: ibuprofen, diclofenac)
- Corticosteroids, such as prednisone, to reduce inflammation and improve mobility
- Ketamine infusion. Ketamine is a strong anaesthetic and low doses delivered as an infusion into a vein can provide substantial pain relief
- Desensitisation of the affected area using techniques such as TENS (transcutaneous electrical nerve stimulation), massage, and brushing of the skin
- Implantation of spinal cord stimulation devices and pain medication-releasing pumps into the spinal canal
- Bisphosphonates, eg: alendronate, which are bone-loss drugs that help to prevent or delay bone loss
- Physiotherapy (exercising affected limb to prevent contractures, maintain muscle strength and movement, and build aerobic fitness)
- Psychological counselling and education regarding the condition
- Relaxation techniques, such as biofeedback and progressive muscle relaxation
- Regular aerobic exercise, eg: swimming / brisk walking.
The most invasive treatment option is chemical or surgical sympathectomy (removal of affected nerves). Surgical sympathectomy involves cutting the nerves and while this can stop pain almost immediately other sensations may be destroyed as well. Limited evidence exists regarding the effectiveness of surgical sympathectomy.
Recovery is variable in CRPS but is likely to be better with early treatment.
Some patients experience recurrences of CRPS, sometimes due to a trigger such as exposure to cold or emotional stress.
Some patients with severe symptoms may not respond to treatment. For these individuals, a pain management programme aimed specifically at chronic pain can be beneficial. This is usually done through a hospital-based multidisciplinary pain clinic involving medical practitioners, physiotherapist, occupational therapists, psychologists, and other health professionals.
Support and information
Living with CRPS can be challenging in terms of maintaining physical and mental health. Community support groups that may be able to assist include:
Complex Regional Pain Syndrome – New Zealand
Phone: (027) 519 9854
Pain Action in New Zealand (PAINZ)
Post: P.O. Box 32 074, Christchurch 8011
Phone: (03) 366 0716
FamilyDoctor.org (2014). Complex regional pain syndrome (Web Page). Leawood, KS: American Academy of Family Physicians. http://familydoctor.org/familydoctor/en/diseases-conditions/complex-regional-pain-syndrome.html [Accessed: 12/05/17]
Mayo Clinic (2014). Complex regional pain syndrome (Web Page). Rochester, MN: Mayo Foundation for Medical Education and Research. http://www.mayoclinic.org/diseases-conditions/complex-regional-pain-syndrome/basics/definition/con-20022844 [Accessed: 12/05/17]
Wheeler, A.H. (2016). Complex pain syndromes (Web page). Medscape Drugs and Diseases. New York, NY: WebMD LLC. http://emedicine.medscape.com/article/1145318-overview [Accessed: 12/05/17]
National Institute of Neurological Disorders and Stroke (2017). Complex regional pain syndrome fact sheet [Web Page]. Bethesda, MD: National Institutes of Health https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Complex-Regional-Pain-Syndrome-Fact-Sheet [Accessed: 12/05/17]
Last Reviewed – May 2017